REI Co-op Frostbreak 5 Sleeping Bag

The REI Co-op Frostbreak 5 is a synthetic-fill mummy bag rated by the manufacturer to -15°C (5°F), built for genuine cold-weather use rather than shoulder-season trips. At 2296 g it's heavy by backpacking standards, but that weight buys synthetic insulation's main advantage over down: it keeps most of its warmth even when damp, which matters for winter car camping. Construction uses a shingled baffle layout to control loft, paired with an insulated draft collar and full-length draft tube along the zipper to seal warmth at the two places mummy bags typically leak heat. The shell is recycled polyester with a DWR finish, and REI notes it as bluesign-approved, though not PFC-free. Sized for sleepers up to 182 cm with a relaxed fit, there's room to layer clothing on cold nights. There's no two-way zipper for venting and no option to couple two bags, and a separate storage sack isn't included — just the compression stuff sack. For winter car camping or cold basecamp nights where pack weight isn't the limiting factor, the Frostbreak 5 trades portability for real cold-weather margin.